Improvement in miniaturized potentiometers

ABSTRACT

A potentiometer having a cover of conductive material formed by molding in a single piece with a pair of lateral terminals provided to be placed at the ends of a resistance track, a collector, and a base on which the resistance track and the collector are printed. The lateral terminals are separated from the cover during the step of crimping the cover on the base.

United States Patent Inventor Eugenio Falco 13, Avenue Taille Bourg,Paris 110, France Appl. No. 801,457 Filed Feb. 24, 1969 Patented May 25,1971 Priority Feb. 27, 1968, Dec. 3, 1968 France 141.458 and 176.382

MINIATURIZED EOTENTIOMETERS 13 Claims, 10 Drawing Figs.

U.S. Cl 338/174, 338/271 Int. Cl l-10lc 9/02 Field of Search 338/134,

[56] References Cited UNITED STATES PATENTS 1 2,160,142 5/1939 l-Iathorn338/271X 2,628,298 2/1953 Budd 338/134 3,069,598 12/1962 Daily 338/3073,111,640 l/1963 Dial 338/160 3,237,140 2/1966 Barden 338/164 3,383,6355/1968 Vananzi 338/162 Primary Examiner-Lewis 1'1. Myers AssistantExaminer-Gerald P. Tolin Attorney-Stevens, Davis, Miller & MosherABSTRAT: A potentiometer having a cover of conductive material formed bymolding in a single piece with a pair of lateral terminals provided tobe placed at the ends of a resistance track, a collector, and a baseonwhich the resistance track and the collector are printed. The lateralterminals are separated from the cover during the step of crimping thecover on the base.

PATENTED was I971 3581265 SHEET 2 0F 3 I nvenlor Buss/v10 FRLCO B7 I lu@11 0/ A tlorneys PATENTEDHAYZSIHH 3.581.265

SHEET 3 BF 3 Invenlor EU. GENIO FRLC 0 army;

MINIATURIZED POTENTIOMETERS This invention pertains to improvedminiaturized potentiometers. Due to the general miniaturization ofelectronic devices, potentiometers designed to be used with printedcircuits should have reduced dimensions.

The potentiometers according to the present invention comprise a simpleand compact potentiometer having a minimum number ofelements.

Such a potentiometer includes a metallic cover which is obtained bymolding. The cover is of a single piece with two lateral terminals whichare positioned at the ends of a resistance track printed on a baseplateand are separated from the cover during the crimping of the cover on thebaseplate.

Out of the assembly, the rotor and the slider are maintained in tightrelationship between the cover and the baseplate.

The rotor is elastically compressed over a large area against the coverand due to this fact, the rotation a friction and the necessary forcesare great, which prevents undesired displacement after adjustment. Therotor does not have any axial play and the force of the slider on thetrack is constant. Finally, the embodiment adapted following the presentinvention enables good protection of the slider and the track.

For attaching the potentiometer to a printed circuit board, theterminals are extended by nondeformable extensions which are molded andhave a circular cross section enabling filling completely the aperturesprovided in the printed circuit plate and to obtain a better solderingthan in the case of exten-- sions formed with rectangular crosssections.

Conforming to the present invention, there is a potentiometer comprisinga cover of conductive material, obtained by molding a single piece witha central terminal provided to be positioned with respect to thecollector and a pair of lateral terminals provided to be positioned atthe ends of a resistance track printed on a base plate of insulatingmaterial, the lateral terminals are separated from the cover during thestep of crimping the cover on the baseplate.

Many other advantages, features and additional objects of the presentinvention will become manifest to those versed in the art. Upon makingreference to the detailed description and the accompanying sheets ofdrawings in which preferred structural embodiments incorporating theprinciples of the present invention are shown by way of illustrativeexample.

ON THE DRAWINGS FIG. 1 is a plan view of one embodiment of apotentiometer in accordance with the invention;

FIG. 2 is an end view of the potentiometer of FIG. 1; FIG. 3 is anextended perspective view of the potentiometer of FIG. 1;

FIG. 3a is a reverse perspective view from that of FIG. 3 of the rotor;

a FIG. 4 is a plan view of an alternative slider;

FIG. 5 is a perspective view of an alternative embodiment of theinvention;

FIG. 6 is a plan view of a further alternative embodiment of theinvention including three potentiometers;

FIG. 7 is a plan view of a further embodiment of the potentiometer ofthe invention including four potentiometers;

FIG. 8 is a cross-sectional view of a further embodiment of theinvention without a rotor; and

FIG. 9 is an extended perspective view of the potentiometer of FIG. 8.

AS SHOWN IN THE DRAWINGS The principles of this invention areparticularly useful when embodied in a potentiometer as illustrated inFIG. I to having a cover I, a rotor 2, a slider 3 and a baseplate 4. Onthe baseplate are screen printed a resistance track 5 and a collector 6.

The cover I, as shown in FIGS. I and 2 before mounting, is made of anelectrically conductive moldable material and has on one of its faces apair of lateral terminals 7, 7a and projections, 8, 8a which engage thebaseplate 4 by means of the apertures 9, 9a. The apertures 9, 9a arepositioned at the ends of the resistance track 5. The cover includes acentral terminal I0. The central terminal 10 has a projection 11 adaptedto be engaged by an aperture 12 positioned at the end of an extension 6aof the collector 6.

The lateral terminals 7, 7a are molded with the cover I at the ends ofapair of webs 13, 13a, respectively.

The cover 1 includes a pair of support feet 14, which with the lateralterminals 7, 7a and central terminal 10 form struts for fixing of thecover 1 on the support plate 4 by means of lips 15, 15a. The lips 15,15a are folded and crimped on the plate 4.

The other face of the cover 1 includes extension members 16, 16a for theterminals 7,- 7a and an extension member 17 for the central terminal 10.

The extension members 16, 16a and 17 are identical and have a circularcross sectionfThe extensions 16, 16a have their axis generallyperpendicular to the face or surface of the cover I. The extensionmembers are adapted to be engaged in the holes of a printed circuit, forexample, by soldering.

The cover 1 includes a bore 18 in which is rotatably mounted a rotatableprojection 19 of the rotor 2. The cover 1 further includes a circularslot 20 in which is engaged a boss 21 of the rotor 2.

The circular slot 20 is interrupted by the stop 22 against which theboss 21 abuts on either side on traversing the slot 20. The distance ofrotation of the rotor 2 is relatively important, approximately 300 withrespect to known types of potentiometers, of similar dimensions.

The rotor 2 is made of insulating material having the general form of adisc 2a and including on the opposite side to the central projection 19and coaxially thereto a rod 23 which is engaged in an aperture 24::provided in the baseplate 4. The rod 23 has at its end a slot 24 inwhich may be engaged the blade of a screwdriver in order to turn therotor.

The rod 23 may also be provided with indentations or a knob to enableturning of the rotor 2 for adjustment of the potentiometer.

During assembly of the cover 1 with the base 4, there is simultaneouslyeffected the separation of the lateral tenninals 7, 7a from the body ofthe cover 1 by separating the webs 13, 13a following the cutting linesx, x, and y, y,.

There is shown an alternative embodiment of potentiometer in FIG. 5 inwhich the rotation axis of the rotor is parallel to the plate carryingthe printed circuit.

This potentiometer comprises a cover 35 and two lateral terminals 34,34a which are fixed on a baseplate 35 as disclosed above.

The rotor 36 extends beyond the edge of the cover 33 and has knurling orindentations 37. The user may manually turn the rotor 36 by means of theindentations in order to make adjustments without being disturbed bycomponents closely positioned to the potentiometer.

The extensions 38, 38a from the terminals 34, 34a, respectively, and theextension 39, from the collector, are positioned with their axisextending perpendicularly to the axis of rotation of the rotor, orparallel to the general axis of the potentiometer.

In the embodiments of FIGS. 6 and 7 are shown several potentiometersgrouped on the same cover.

Three potentiometers 40a, 40b, 40c, are mounted on the cover 4I which ismolded with the terminals 42a, 42b, 42c, for each potentiometer, shownonly for potentiometer 400, FIG. 6.

The terminals 42 and the three potentiometers are positioned betweenthemselves and the cover 41 by a linking bar 43. The linking bar 43 isseparated from the cover 41 and the terminals 42 following three cuttinglines such as a, a b, b,, and c, c, when crimping the cover 41 on thebaseplate of the potentiometers.

In a further embodiment four potentiometers 44a, 44b, 44c, 44d, aregrouped on the cover 45, FIG. 7.

The potentiometers are grouped in pairs, that is, 44a, 44b, and 44c, 44dand the terminals of each such as 46a, 46b, 46c are positioned withrespect to the cover 45 by two linking bars 47 and 48 which are outalong cutting lines as disclosed above.

Where in certain applications of adjustable potentiometers, the controlrod of the rotor is not utilized and it is not necessary to insulate theadjustment means of the potentiometers from the slider.

Effectively, it is possible to provide on the slider a slot in which maybe engaged the end of a screwdriver in order to move the slider andadjust the device.

In this case, it is possible to eliminate from the potentiometerdescribed above, the rotor made of insulating material and to utilize aslider which is compressed elastically between the cover and thebaseplate of insulating material on which are printed the resistancetrack and the collector. Good contacts are thereby achieved between theslider and the resistance track and collector as well as preventingundesired movements of the slider.

This embodiment of potentiometer is especially economical and may bemade with a minimum of elements.

Moreover, the potentiometer of this embodiment is capable of beingautomatically mounted, as the three pieces are of simple structure,strong and of large dimensions relative to the dimensions of the device.

As shown in FIGS. 8 and 9 such an alternative embodiment ofpotentiometer includes a coverl, which is made according to the processof the invention and includes support feet 52, whose ends 52a are turneddown on the baseplate 53 which is identical to the baseplate 4. Thebaseplate 53 is made of insulating material and has a resistance track54 and a collector 55 thereon.

Between the cover 51 and the baseplate 53 is elastically engaged inmounting a slider 56 made of a generally annular metallic member 57,which is suitably bent. The mcmber'57 through the projection 58 engagesthe resistance track 54 and through the projection 59 engages thecollector 55. The annular member 57 is positioned by the radial arms61a, 61b with respect to a central member 60 which guides and drives theannular member 57. The central member 60 is in the shape of a truncatedcone.

The central member 60 is engaged in a correspondingly shaped housing 62,in the form of a truncated cone, in a manner to assure the centering ofthe slider 56 with respect to the cover 51 and the baseplate 53.

The central member 60 is compressed elastically between the truncatedcone housing 62 and the friction of these conical surfaces against eachother creates a turning force proportional to the angle of the cone. Theforce is sufficiently great in order to prevent the displacement of theslider under the effect of shocks and vibrations.

The member 60 has an adjustment slot 63 in which may be engaged a blade64 of a screwdriver either through the opening 65 provided in the cover5], or through the opening 66 provided in the baseplate 53, the openings65 and 66 being situated concentrically to the housing 62.

On the base of the central member 60 there is provided a foot 67 whichextends radially and whose edges 68a, 68b are capable of coming instopping contact with the edges 69a, 69b of a boss 70 attached to thecover 51 and projecting towards the slider 56. The post 67 and the boss70 thereby limit the radial movement of the slider. Thus in abutting theboss 70 on either edge 69a, 69b, the foot 67 limits the radial movementof the slider 56.

Although many modifications may be suggested by those versed in the art,it should be understood that 1 wish to embody within the scope of thepatent warranted hereon all such embodiments as reasonably and properlycome within the scope of my contribution to the art.

lclaim:

l. A potentiometer device comprising in combination: a conductive coverformed as a single piece molding with a central terminal; a baseplate ofinsulating material fixed on said cover by means of lips folded andcrimped on said plate; a resistance track and collector printed on saidbaseplate, said collector having an aperture in which is engaged aprojection of thecentral terminal, said resistance track havingapertures in which are engaged projections of 'at least one pair oflateral terminals, at least one rotor of insulating material; at leastone slider, said slider being operatively associated with said rotor andin contact with said resistance track and said collector.

2. A potentiometer according to claim 1, wherein said slider is ofannular metallic form, said slider having an aperture and a slotdiametrically positioned,'the aperture and the slot being engaged by apair of knobs projecting from the disc of said rotor, the aperture andthe slot being positioned at equal distances between the points ofcontact of said slider with said resistance track and said collector.

3. A potentiometer according to claim 2 wherein the points of contact ofsaid slider are a pair of feet one of which is in contact with saidresistance track and the other being in contact with said collector.

4. A potentiometer according to claim 3 including extension meansextending from each of said terminals, said central terminal extensionmeans being molded with said cover and extending perpendicularlytherefrom.

5. A potentiometer according to claim 3, including extension meansopcrativcly connected to said central terminal molded with said coverand extending parallel to the plane of said cover.

6, A potentiometer according to claim 5, wherein said extension meanshave circular cross sections.

7. A potentiometer according to claim 2, including a rod extending fromsaid rotor, said rod having a slot capable of being engaged by anadjustment tool.

8. A potentiometer according to claim 2 wherein said rotor is providedwith a knurled outer edge.

9. A potentiometer according to claim 2, wherein the disc of said rotoris elastically deformable.

10. A potentiometer according to claim 4, wherein said central terminalextension means has a circular cross section.

11. A potentiometer according to claim 1, including a slider having acentral member in the form of a truncated cone received in acorrespondingly shaped recess in said cover, said central memberincluding a slot in which may be engaged an adjustment tool.

12. A potentiometer according to claim 11, wherein said central memberhas a foot and said cover has a boss forming a stop with the foot andthereby limit the radial movement of said slider.

13. A potentiometer according to claim 11, wherein said cover and saidbaseplate have openings through which the adjustment tool may pass toengage the slot of said central member.

1. A potentiometer device comprising in combination: a conductive coverformed as a single piece molding with a central terminal; a baseplate ofinsulating material fixed on said cover by means of lips folded andcrimped on said plate; a resistance track and collector printed on saidbaseplate, said collector having an aperture in which is engaged aprojection of the central terminal, said resistance track havingapertures in which are engaged projections of at least one pair oflateral terminals, at least one rotor of insulating material; at leastone slider, said slider being operatively associated with said rotor andin contact with said resistance track and said collector.
 2. Apotentiometer according to claim 1, wherein said slider is of annularmetallic form, said slider having an aperture and a slot diametricallypositioned, the aperture and the slot being engaged by a pair of knobsprojecting from the disc of said rotor, the aperture and the slot beingpositioned at equal distances between the points of contact of saidslider with said resistance track and said collector.
 3. A potentiometeraccording to claim 2 wherein the points of contact of said slider are apair of feet one of which is in contact with said resistance track andthe other being in contact with said collector.
 4. A potentiometeraccording to claim 3 including extension means extending from each ofsaid terminals, said central terminal extension means being molded withsaid cover and extending perpendicularly therefrom.
 5. A potentiometeraccording to claim 3, including extension means operatively connected tosaid central terminal molded with said cover and extending parallel tothe plane of said cover.
 6. A potentiometer according to claim 5,wherein said extension means have circular cross sections.
 7. Apotentiometer according to claim 2, including a rod extending from saidrotor, said rod having a slot capable of being engaged by an adjustmenttool.
 8. A potentiometer according to claim 2 wherein said rotor isprovided with a knurled outer edge.
 9. A potentiometer according toclaim 2, wherein the disc of said rotor is elastically deformable.
 10. Apotentiometer according to claim 4, wherein said central terminalextension means has a circular cross section.
 11. A potentiometeraccording to claim 1, including a slider having a central member in theform of a truncated cone received in a correspondingly shaped recess insaid cover, said central member including a slot in which may be engagedan adjustment tool.
 12. A potentiometer according to claim 11, whereinsaid central member has a foot and said cover has a boss forming a stopwith the foot and thereby limit the radial movement of said slider. 13.A potentiometer according to claim 11, wherein said cover and saidbaseplate have openings through which the adjustment tool may pass toengage the slot of said central member.